AT LEAST 50 people have been killed in a series of attacks spread over a wide area of Iraq.

It's understood the bombings were targeting mostly security forces in what appeared to be another strike by al Qaida militants

The apparently co-ordinated blasts and shootings unfolded over two and a half hours in Baghdad - where most of the deaths were - and 11 other cities.

They struck government offices, restaurants and also close to a primary school in the town of Musayyib. More than 200 people were injured.

Nationwide, security forces appeared to be targeted in at least 14 separate attacks, including a drive-by shooting in Baghdad that killed six policemen at a checkpoint before dawn.

Police patrols in the capital and beyond were besieged by roadside bombs and, in once case, a suicide bomber who blew up his car outside a police station in the city of Baqouba, 35 miles north east of Baghdad.

While no group immediately claimed the attacks, targeting security officials is a hallmark of al Qaida in Iraq. In December, a wave of bombs tore through mostly Shiite neighbourhoods of Baghdad, killing 69 people in a similar onslaught of violence that Sunni-dominated al-Qaida claimed.

There have been a series of large-scale attacks by insurgents since the last US troops left Iran in mid-December at the end of a nearly 10-year war.

Shortly after the withdrawal, a major political crisis with sectarian undertones erupted when Shiite-dominated authorities sought to arrest Sunni vice president Tariq al-Hashemi on allegations he commandeered death squads targeting security forces and government officials.

Iraq's police are generally considered to be the weakest element of the country's security forces, and 20 were killed earlier this week by a suicide bomber outside the Baghdad police academy.

But the latest violence spilled on to commuters, restaurant patrons, passers-by and schoolchildren as well.

In the single deadliest strike, a car bomb in Baghdad's shopping district of Karradah killed nine people and wounded 26. The blast effects could be felt blocks away, shaking buildings and windows.

In Musayyib, a car bomb parked on the street between a restaurant and a school killed one person and wounded 62. Most of the injured were schoolchildren, said police and health officials.

The casualties were tallied by local security and hospital officials in the cities where the attacks occurred.

Late on Wednesday, the interior ministry announced the capture of Waleed Khalid Ali, accused as a top leader of the Ansar al-Sunna insurgent group linked to al Qaida. The government said Ali was caught trying to enter Iraq from Syria, where al Qaida groups have been surging to assist opposition forces seeking the overthrow of President Bashar Assad.

But the co-ordinated nature of today's attacks suggest they were planned long before the arrest. A Western diplomatic security official said recent intelligence indicated that an unspecified attack was in the works.